Method and device for cleaning the atmosphere

ABSTRACT

Method for treating atmospheric pollutants by contacting the atmosphere with a catalyst composition or adsorptive material coated on the surface of a substrate in which the catalyst composition or adsorptive material is protected from degradation by harmful contaminants contained in the atmosphere by a coating of at least one porous protective material and a device useful therefor.

FIELD OF THE INVENTION

[0001] The present invention relates to a method for the low temperaturecleaning of the atmosphere and more particularly to the rendering of theouter surface of a substrate, such as a radiator of a motor vehicle,capable of either catalytically converting atmospheric pollutants toless harmful materials or adsorbing such pollutants without adverselyaffecting the functioning of the substrate. The method is accomplishedthrough the employment of a pollutant treatment coating on the surfaceof such substrate said coating being further provided with anovercoating of either a protective material alone or in combination witha water repellant material which improves durability and long termperformance of the catalytic or adsorptive coating.

BACKGROUND OF THE INVENTION

[0002] A review of literature relating to pollution control reveals thatthe general approach is to reactively clean waste streams entering theenvironment. If too much of one pollutant or another is detected orbeing discharged, the tendency has been to focus on the source of thepollutant. For the most part gaseous streams are treated to reduce thepollutants prior to entering the atmosphere.

[0003] It has been disclosed to treat atmospheric air directed into aconfined space to remove undesirable components therein. However, therehas been little effort to treat pollutants which are already in theenvironment; the environment has been left to its own self-cleansingsystems.

[0004] References are known which disclose proactively cleaning theenvironment. U.S. Pat. No. 3,738,088 discloses an air filtering assemblyfor cleaning pollution from the ambient air by utilizing a vehicle as amobile cleaning device. A variety of elements are disclosed to be usedin combination with a vehicle to clean the ambient air as the vehicle isdriven through the environment. In particular, there is disclosedducting to control air stream velocity and direct the air to variousfilter means. The filter means can include filters and electronicprecipitators. Catalyzed postfilters are disclosed to be useful to treatnon-particulate or aerosol pollution such as carbon monoxide, unburnedhydrocarbons, nitrous oxide and/or sulfur oxides, and the like.

[0005] Another approach is disclosed in U.S. Pat. No. 5,147,429. Thereis disclosed a mobile airborne air cleaning station. In particular thispatent features a dirigible for collecting air. The dirigible has aplurality of different types of air cleaning devices contained therein.The air cleaning devices disclosed include wet scrubbers, filtrationmachines, and cyclonic spray scrubbers.

[0006] The difficulty with devices disclosed to proactively clean theatmospheric air is that they require new and additional equipment. Eventhe modified vehicle disclosed in U.S. Pat. No. 3,738,088 requiresducting and filters which can include catalytic filters.

[0007] DE 40 07 965 C2 to Klaus Hager discloses a catalyst comprisingcopper oxides for converting ozone and a mixture of copper oxides andmanganese oxides for converting carbon monoxide. The catalyst can beapplied as a coating to a self-heating radiator, oil coolers orcharged-air coolers. The catalyst coating comprises heat resistantbinders which are also gas permeable. It is indicated that the copperoxides and manganese oxides are widely used in gas mask filters and havethe disadvantage of being poisoned by water vapor. However, the heatingof the surfaces of the automobile during operation evaporates the water.In this way, continuous use of the catalyst is possible since no dryingagent is necessary.

[0008] Responsive to the difficulties associated with devices whichproactively treat the atmosphere, the Assignee herein in U.S. patentapplication Ser. No. 08/410,445 filed on Mar. 24, 1995, U.S. patentapplication Ser. No.08/589,182 filed Jan. 19, 1996, and U.S. patentapplication Ser. No. 08/589,030 filed Jan. 19, 1996, each incorporatedherein by reference, disclosed apparatus in related methods for treatingthe atmosphere by employing a moving vehicle. In preferred embodiments aportion of the surface of the engine or cabin cooling system (e.g. theradiator, air-conditioning condenser, etc.) is coated with a catalyticor adsorption composition. Additionally, the fan associated with theengine cooling system can operate to draw or force air into operativecontact with the radiator. Pollutants contained within the air such asozone, hydrocarbons and/or carbon monoxide are then catalyticallyconverted to non-polluting compounds (e.g., oxygen, water and carbondioxide).

[0009] The Assignee herein also has pending U.S. patent application Ser.No. 08/412,525 filed on Mar. 29, 1995, incorporated herein by reference,which discloses devices and methods for proactively treating theatmosphere catalytically by employing a stationary object such asselected surfaces of an automobile at rest, a billboard, an airconditioning unit and the like coated with a catalytic composition.

[0010] In addition, International Publication No. WO 98/02235 of theAssignee herein discloses a process of catalytically activating thesurface of a heat exchange device such as a motor vehicle radiator whileretaining the heat exchange properties of the device. The method enablesthe catalytic treatment of the atmosphere by converting pollutantscontained therein to less harmful materials while allowing the radiatorto perform its function normally. A polymeric protective coating whichis stable up to temperatures of about 100° C. may be employed to retarddegradation and inactivation of the catalyst.

[0011] The application of a catalyst or absorbent composition to thesurface of a substrate such as a radiator of a motor vehicle presentsproblems such as the exposure of the composition to relatively highconcentrations of contaminants which can deleteriously affect thefunctioning of the composition. Such contaminants include solid orvaporized particulates, corrosive compounds such as salts and oxides ofnitrogen, sulfur and the like. Contact of the composition with suchcontaminants can result in masking, fouling and/or poisoning. Inaddition, water (and contaminants contained therein) can be a source ofdegradation and can also decrease the activity and useful life ofcatalyst and adsorbent compositions.

[0012] It would therefore be a significant advance in the art ofreducing atmospheric pollution to employ catalytic and adsorptivecomposition coated devices for the treatment of the atmosphere to removepollutants contained therein wherein the composition is protectedagainst those contaminants commonly encountered in the atmosphere whichcan adversely affect performance of the composition. It would be afurther advance in the art if the composition could be protected fromcontaminants at from ambient temperatures up to about several hundreddegrees centigrade. It would be still a further advance in the art ifthe composition could be protected from water especially liquid water.

SUMMARY OF THE INVENTION

[0013] The present invention generally relates to a method and devicefor cleaning the atmosphere by removing pollutants therefrom. A surfacewhich contacts the atmosphere such as a surface of a radiator of a motorvehicle is treated with a catalyst or absorbent composition so that theouter surface (i.e., air side) thereof is capable of either adsorbingpollutants or catalytically converting pollutants contained in theatmosphere into less harmful substances. The composition is coated atleast in part (preferably completely) with a porous, protective coatingas defined herein which effectively protects the composition fromatmospheric contaminants at ambient temperatures up to several hundreddegrees centigrade or higher. Preferably, the porous protective coatingis itself overcoated with a hydrophobic material. The present inventionalso encompasses devices treated in the manner described herein.

[0014] The term “adsorption” is defined as including: (a) thepenetration of one substance into the inner structure of another(commonly referred to as “absorption”); and (b) adherence of the atoms,ions, or molecules of a gas or liquid to the surface of anothersubstance (commonly referred to as “adsorption”). See, for example,Hawley's Condensed Chemical Dictionary, Thirteenth Edition, Van NostrandReinhold, 1997, pp. 2, 3, 24.

[0015] Similarly, related terms such as, for example, adsorbents,adsorbing, adsorptive, etc. shall be understood to include both relatedmeanings. The term “atmosphere” means the mass of air surrounding theearth, and includes “ambient air” which is the portion of the atmospherethat is drawn or forced towards the outer surface of the coatedsubstrate. Ambient air includes air, which has been heated eitherincidentally or by a heating means. The term “substrate” is used in itscustomary broad sense and includes any surface which can be coated witha suitable catalyst or adsorbing composition and thereafter have thecomposition protected in the manner described herein. Such surfacesinclude those surfaces found in motor vehicles such as automobiles,trucks, vans, buses, trains, airplanes and the like and include but arenot limited to radiators, condensers, charge air coolers, transmissioncoolers, inserted devices which may be separately heated, heatexchangers, fluid transporting conduits and the like. Surfaces normallydescribed as stationary such as billboards, road signs, outdoor HVACequipment are also included. For convenience only, a motor vehicleradiator will be discussed herein as typical of a suitable substrate.

[0016] In accordance with the present invention, the surface of thesubstrate (e.g., radiator) is provided with a substance which can eithereffectively catalyze the conversion of pollutants contained in theatmosphere to less harmful substances or adsorb such pollutants forlater treatment as appropriate. The surface of the radiator is thereforecapable of either catalytically converting pollutants such ashydrocarbons, carbon monoxide and ozone into less harmful materials suchas oxygen, carbon dioxide and water, or adsorbing pollutants such asNOx, SOx hydrocarbons and carbon monoxide as the case may be.

[0017] In one aspect, the present invention is directed to a method ofcatalytically treating the atmosphere to convert pollutants to lessharmful materials comprising treating an outer surface of a substrate,particularly an auto radiator to render said surface capable ofcatalytically converting said pollutants and then providing the catalystwith an overcoating of at least one material or mixtures of suchmaterials which is porous and preferably also adsorbent (hereinafter,“porous protective material”). The porous protective material ispreferably sufficiently porous to enable the atmosphere including thecontained pollutants to be treated to pass therethrough into operativecontact with the catalyst composition to enable conversion thereof intoless harmful materials. The porous protective material preferably shouldalso be adsorbent in order to trap atmospheric catalyst degradatingcontaminants so that they are at least substantially prevented fromreaching the catalyst composition. Still further, the catalyst and theporous protective material are preferably stable at ambient temperaturesand up to about several hundred degrees centigrade.

[0018] In another aspect of the invention, the porous protectivematerial may include or be overcoated with at least one substance whichis capable of protecting the catalyst composition from contact withliquid water and/or water vapor (hereinafter, “hydrophobic protectivematerial”).

[0019] In another aspect of the invention, the outer surface of thesubstrate (e.g. radiator) is made of or provided with a catalyticallyactive substance such as a base metal catalyst (e.g. manganese dioxide),precious metal catalyst or combination thereof. As used herein the terms“base metal catalyst” and “precious metal catalyst” shall include thebase metals and precious metals themselves as well as compoundscontaining the same e.g., salts and oxides and the like.

[0020] In another aspect, the present invention is directed to a methodfor cleaning the atmosphere comprising treating an outer surface of asubstrate, particularly an auto radiator with an adsorptive material torender said surface capable of adsorbing pollutants present in theatmosphere such as NOx, SOx hydrocarbons and carbon monoxide and thenproviding the adsorptive material with an overcoating of at least oneporous protective material.

[0021] In another aspect of the invention, the outer substrate surfacecoated with either a catalyst composition or adsorbing composition, iscoated with the porous protective material which is then overcoated witha hydrophobic protective material. The protective material, whetherporous, hydrophobic or a combination of both still permits pollutants topass into contact with either the catalyst composition so they may beconverted to less harmful materials or into contact with the adsorbingcomposition so that they may be absorbed and thereby removed from theatmosphere.

[0022] The coatings contemplated for use herein do not substantiallyinterfere with the normal desired operation of the substrate (e.g., autoradiator) whose surface has been coated.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The following drawings in which like reference charactersindicate like parts are illustrative of embodiments of the invention andare not intended to limit the invention as encompassed by the claimsforming part of the application.

[0024] FIGS. 1A-1F are cross-sectional views showing variousarrangements of the catalyst or adsorbing composition and protectivematerial of the present invention.

[0025]FIG. 2 is a side view of a radiator assembly of a motor vehicle;and

[0026]FIG. 3 is an enlarged cross-sectional view of a motor vehicleradiator.

DETAILED DESCRIPTION OF THE INVENTION

[0027] The present invention is directed to a method of cleaning theatmosphere by treating the surface of a substrate (e.g. a motor vehicleradiator) so that pollutants contained in ambient air upon contact withsaid surface may either be readily converted catalytically to lessharmful materials or removed by adsorption. For example, (a) the surfaceof the substrate may be rendered catalytic if the surface is providedwith catalytically active materials or a catalyst composition or thesurface itself may be made of a catalytically active material; or (b) anadsorptive composition may be applied to the surface of the substrate.Thus, the present invention is particularly adapted to either thecatalytic conversion of hydrocarbons, ozone and carbon monoxide intoless harmful materials such as oxygen, carbon dioxide and water or theremoval of e.g., NOx, SOx, hydrocarbons and carbon monoxide byadsorption.

[0028] In accordance with the present invention, the surface coat of thecatalyst or adsorptive composition is overcoated with a porousprotective material which is porous and adsorbent. The term “porous”means that the material allows the ambient air containing pollutantssuch as hydrocarbons, ozone, carbon monoxide and the like to passthrough the porous protective material to effectively contact thecatalyst and adsorptive composition and thereby be converted to lessharmful materials. The term “adsorbent” when used herein means thatundesirable contaminants such as particulate matter, high molecularweight hydrocarbons, water borne salts, aerosols, gases (e.g. NOx, SOx),and the like which can mask, foul and/or poison the catalyst compositionor interfere with the functioning of the adsorptive composition areadsorbed, trapped and may be retained in the porous protective materialso that they are maintained out of contact with the underlying activecomposition.

[0029] In a further aspect of the present invention, the porousprotective material may optionally include or may be overcoated with ahydrophobic material which substantially prevents water (liquid orvapor) from contacting the catalytic or adsorptive composition. It hasbeen observed that in the presence of liquid water and the contaminantsthat may be contained therein, degradation of the catalyst compositionis accelerated and conversion rates of pollutants to less harmfulmaterials are more quickly degraded than in the absence of liquid waterand the contained contaminants. It is anticipated that adsorptivecompositions will similarly benefit from protection from water.

[0030] In a still further aspect of the invention, the catalytic oradsorptive composition coated on the substrate may first be coated withthe hydrophobic protective material and the porous protective materialis coated over it.

[0031] For reasons of convenience, the invention will be furtherdescribed and exemplified using its catalytic embodiment. Those skilledin the art will appreciate that the adsorptive embodiment of theinvention can be substituted and applied and utilized in a substantiallysimilar manner as described for the catalytic embodiment usingsubstantially similar techniques.

[0032] The atmosphere contacting surface is the outer surface of anydevice such as a motor vehicle radiator which can effectively receivethe catalyst composition and overcoat of the protective material(s) andwhich comes into contact with a pollutant-containing gas such as ambientair. Any device in which there is a flow of ambient air thereover ortherethrough may be treated in accordance with the present invention. Ofparticular importance to the present invention is the rendering of theouter surface of the substrate (e.g., radiator) capable of catalyticallyconverting pollutants to less harmful materials without adverselyaffecting the substrate and its function. Thus, if the substrate is aradiator, the catalyst composition and protective material overcoat(s)shall not substantially adversely affect either the heat exchangeproperties or the physical integrity of the radiator. The catalystcomposition is protected by at least one porous, preferably adsorbentprotective material to insure against premature degradation of thecatalyst composition and optionally one hydrophobic protective materialto protect the catalyst composition from water (liquid and/or vapor).The porous protective material and the hydrophobic protective materialmay also be mixed and coated onto the catalyst composition as one layer.

[0033] A particular embodiment of the present invention is directedtowards protective materials and methods for improving the durability ofcatalysts used for treating the atmosphere. Such catalysts include, forexample, ozone converting catalytic compositions (especiallycompositions containing MnO₂), and catalysts useful for treating carbonmonoxide and hydrocarbons as well. Manganese dioxide is a particularlypreferred catalyst material for use in the present invention to treatozone, and precious metals such as platinum and/or palladium arepreferred to treat hydrocarbons and carbon monoxide.

[0034] In this embodiment, the invention is specifically directed to theuse of protective materials which may be overcoated on catalytic systems(e.g., catalyst coated automobile radiators) which are useful forcleaning the atmosphere by catalytically treating pollutants containedin the atmosphere. The function of the protective materials is toprevent atmospheric catalyst degrading contaminants (e.g., solid oraerosol particulates, water, SOx, NOx, water borne salts, high molecularweight hydrocarbons, etc.) which lead to masking, fouling, and/orpoisoning of the catalyst composition from interacting with the catalystcomposition. Since the purpose of an automobile radiator is to provideheat exchange and cooling for the engine, the radiator is usuallylocated at the front of the vehicle where it has ample access to largevolumes of ambient air. As a result, the radiator operates in arelatively dirty environment and is exposed to all types of solid,gaseous and liquid airborne and roadway contaminants. A catalystcomposition applied to the radiator for purposes of treating atmosphericpollutants such as ozone should preferably be able to function over anextended period of time in a severely dirty environment. Long term roadtests of ozone destruction catalysts applied to automobile radiatorshave shown that deactivation of catalyst performance occurs over time asthe mileage on the vehicle increases. Visual inspection of prior artradiators which had been surface coated only with an ozone catalyst,e.g., a MnO₂ containing catalyst and removed from service after extendedon-road aging (e.g., 50,000 or 100,000 miles) showed the readilyapparent deposition of dirt, salts, and other solid contaminants on thesurface of the catalyst composition. These unprotected compositionssuffered a significant loss of activity measured at about 50% or higher.Chemical analyses also confirmed the deposition of sulfate, sodium,chloride, calcium, silica, alumina and carbon on the catalystcomposition. Although many mechanisms may exist for deactivation of suchroad-aged catalysts, it is believed that deposition of atmosphericcontaminants (particularly SOx aerosols, and particulate matter bothlarge and small) account for a significant decrease in catalystperformance over time.

[0035] The practice of the methods of the present invention minimizecontact of airborne contaminants with the radiator catalyst composition.This is accomplished by applying an overcoat of a porous, preferablyadsorbent protective material on the surface of the catalystcomposition. The function of the porous protective material is to trapand hold airborne particulates, high molecular weight hydrocarbons,aerosols, water borne salts and catalyst deactivating gases such as SOx,so that they do not come into contact with the active catalystcomposition underneath. The porous protective material is preferablydense enough to trap contaminants but also porous enough to allow freepassage of the ambient air which contains the pollutant to be treated(e.g. ozone, hydrocarbons, carbon monoxide) to the catalyst compositionbelow. In this way, the catalyst composition is kept substantiallycontaminant free and is therefore able to provide high levels of longlasting pollutant conversion.

[0036] Suitable porous protective materials may include, but are notlimited to zeolites, clays, alumina, silica, alkaline earth oxides, rareearth oxides, carbon, inert metal oxides as well as mixtures thereof.

[0037] The zeolites for use in the present invention as the protectivematerial include acid and/or ion exchanged and/or dealuminated zeolitesexamples of such zeolites include but are not limited to zeolite-Y,ferrierite, zeolite-A, beta-zeolite, ZSM-5, other molecular sieves andmixtures thereof.

[0038] Clays include, for example, attapulgite, kaolin and mixturesthereof.

[0039] Aluminas include, silica alumina, gamma alumina, alpha alumina,colloidal alumina, and mixtures thereof including those having high andlow surface areas.

[0040] Typical useful silicas include silicalite, silica gel, fumedsilica, aerogels, high silica content silica-aluminas, colloidal silicaand mixtures thereof.

[0041] Examples of useful alkaline earth oxides include calciumoxide/hydroxide, calcium magnesium aluminates, barium carbonate, bariumoxide/hydroxide, strontium carbonate, strontium oxide/hydroxide, spinelsand mixtures thereof.

[0042] Typical and useful rare earth oxides include ceria, lanthana andmixtures thereof.

[0043] Examples of carbon for use in the present invention includegranular activated carbon, carbon black, permanganate on carbon andmixtures thereof.

[0044] In addition to the examples mentioned above inert metal oxidessuch as, for example, titania, zirconia, silica, and mixtures thereofcan be employed as the protective material.

[0045] The preferred porous protective material for use in the practiceof the invention is aluminum oxide, more preferred is high surface areasilica containing aluminum oxide

[0046] Protective materials may optionally also be combined with and mayinclude hydrophobic substances which render the area around the catalystcomposition water repellant. The hydrophobic material may also beprovided as a separate overcoat either over or under the porouscomponent. Suitable hydrophoblic substances for use in the presentinvention include, but are not limited to water dispersible polymers,polymer emulsions such as fluoropolymer water based latex emulsions(FC-824 and FC-808 manufactured by 3M Company) and water based Teflonemulsions (e.g. TF5035 manufactured by 3M Company), and siliconepolymers, such as water based silicone emulsions (e.g. BS-1306 andBS-1001A manufactured by Wacker Silicones Corp.). The protectivematerial, as more fully explained hereinafter, may be applied by anynumber of methods such as dipping or spraying a slurry containing theprotective material. The porous protective material and the optionalhydrophobic protective material may each be applied in separate layersto the catalytic surface or they may be applied as a mixture.

[0047] The protective material may be employed to cover a variety ofcatalyst compositions. As previously indicated, such catalystcompositions include base metals, precious metals, salts and oxidesthereof and combinations thereof. Manganese dioxide is an especiallypreferred catalytic material especially for the conversion of ozone. Itis also anticipated that manganese dioxide will itself be useful as theporous protective material for overcoating and protecting catalystcoatings when practicing the catalytic embodiment of the invention.

[0048] The base metals which may be employed for the catalystcomposition include all base metals which can effectively convert ozoneto oxygen and/or carbon monoxide to carbon dioxide. The preferred basemetals include manganese, iron, copper, chromium, and zinc compoundscontaining the same and combinations thereof. The base metals aretypically used in the form of oxides.

[0049] The precious metals are preferably selected from thosecustomarily used in catalyst compositions for the purification of engineexhaust, e.g., platinum, palladium, rhodium and mixtures thereof. Silverand gold may also be used.

[0050] The catalyst composition may also be provided with a suitablesupport material which preferably has a high surface area. The preferredsupport materials are refractory oxides such as those selected from thegroup consisting of ceria, alumina, titania, silica, zirconia, andmixtures thereof with alumina being the most preferred refractory oxidesupport. It is preferred that the refractory oxide support have a highsurface area to maximize the amount of the catalytic material within agiven unit area. The term “high surface area” as it pertains to therefractory oxide support shall generally mean that the surface area ofthe support is at least 100 m²/g preferably in the range of from about100 to 300 m²/g.

[0051] The catalyst composition may be applied to the radiator surfaceby techniques commonly used in the industry, e.g., dipping and/orspraying.

[0052] The catalyst compositions described above once deposited or madepart of the substrate are then protected with at least one protectivematerial, preferably, a porous material having adsorbent properties andmixtures thereof as described above. The porous protective material maybe in the form of a single layer or multiple layers lying between thecatalyst composition and the atmospheric airflow containing thepollutants which are to be treated. The same or different protectivematerials may be used for the multiple layer configuration optionallyincluding one or more layers of a hydrophobic protective material asdescribed previously. For example, the catalyst composition as depositedon the surface of the substrate may be overcoated with one or morelayers of a porous protective material such as alumina with the aluminacoating optionally having one or more layers of a hydrophobic protectivematerial (e.g. latex based emulsion) coated thereover.

[0053] In an alternative embodiment, the protective materials mayencapsulate the catalyst composition. Such encapsulated catalystcompositions may be prepared by coating individual particles of thecatalyst composition by dipping or spraying with a slurry containing oneor more protective materials, e.g., the porous protective materialand/or the hydrophobic protective material.

[0054] In operation of the present invention, ambient air is drawn orforced over the catalytic surface by natural wind currents or by airdrawing devices such as fans. For land use motor vehicles, the radiatorsurfaces are preferably the surfaces which are coated with the catalystcomposition, and the air drawing device is the motor vehicle radiatorfan. It should be understood, however, that other substrates such as airconditioning condensers, charge air coolers, transmission coolers,inserted devices which may be separately heated and the like may betreated in a like manner.

[0055] In a preferred embodiment of the present invention, theatmosphere contacting surfaces are appropriate surfaces of a motorvehicle radiator, particularly in automobile radiator. By treating theradiator surface as described herein pollutants can be readily removedfrom the atmosphere while the catalyst is able to maintain usefulconversion rates for extended periods of time. The normal function ofthe radiator is not substantially affected by the coating(s).

[0056] The present invention will be better understood by those skilledin the art by reference to accompanying FIGS. 1-3. What is particularlyimportant in accordance with the present invention is that the catalystcomposition is protected from degrading contaminants by the applicationof at least one protective material as described herein. As the ambientair encounters the catalytic surface of e.g., the radiator,hydrocarbons, carbon monoxide and/or ozone are catalytically reacted toproduce less harmful materials such as oxygen, carbon dioxide, and watervapor. Additionally, gaseous contaminants such as high molecular weighthydrocarbons, SOx and NOx and other contaminants such as dirt, carbon,aerosols, particulates, water, water borne salts, soil and the like arekept away from the catalyst composition through the use of theprotective material(s).

[0057] It will be appreciated by those skilled in the art that when thesubstrate is associated with a vehicle, any suitable vehicle can beemployed. Vehicles include cars, trucks, trains, boats, ships,airplanes, dirigibles, balloons, and the like. Preferably in a motorvehicle, the atmosphere contacting surfaces are surfaces located towardthe front of the vehicle in the vicinity of the cooling system fan.Useful contact surfaces include the outside (i.e. airside) surfaces ofthe radiator, air conditioner condenser, and the like which are alllocated and supported within the housing of the vehicle.

[0058] In a preferred embodiment of the invention the protectivematerial includes a hydrophobic substance which functions to protect thecatalyst composition from liquid water and/or water vapor. Thehydrophobic protective material is preferably applied as a separatelayer or layers either directly over the porous protective overcoatcoated on the catalyst composition or indirectly thereover (i.e. whereinthe hydrophobic protective material coating layer is between thecatalyst composition surface coating and the porous protective materiallayer). As an alternative, the hydrophobic substance may be incorporatedinto one or more porous protecting material coating layers, or may beused in conjunction with one or more other protective materials toencapsulate the catalyst and/or adsorbent composition prior to coatingthe support. The hydrophobic substance may also be used as the onlyprotective material to overcoat the catalyst or adsorptive substratecoating.

[0059] The hydrophobic protecting material can prevent liquid waterand/or water vapor from contacting the catalyst composition and is atleast substantially stable under the temperature conditions typicallyassociated with a substrate such as a motor vehicle radiator. Thehydrophobic protecting material will be stable at temperatures fromabout 0 to 300° C., preferably 0 to 200° C., more preferably 0 to 150°C. and most preferably 0 to 100° C.

[0060] Various arrangements of the protective material optionallyincluding a hydrophobic substance and the catalyst composition are shownin FIGS. 1A-1E. Although single overcoats of the porous and hydrophobicprotective coatings and the components thereof are depicted in theFigures, it will be appreciated that multiple coats either alternatingor continuous are also within the scope of the invention.

[0061] Referring to FIG. 1A there is shown a first arrangement inaccordance with the present invention in which a substrate 100, such asa radiator, is coated with a catalyst or adsorptive (collectivelyhereinafter, “active”) composition layer 102 and a coating layer 104thereover comprising a porous, adsorbent material such as alumina,silica or mixture thereof.

[0062] The present invention may optionally provide for a hydrophobiclayer as described previously. Referring to FIGS. 1B-1D and first toFIG. 1B, the hydrophobic layer 106 is placed above the coating layer104. The hydrophobic layer 106 provides water repellency to thesubstrate and thereby prevents water from adversely affecting the activecomposition.

[0063] In an alternative embodiment, the hydrophobic layer 106 is placedbetween the coating layer 104 and the active composition 102 as shown inFIG. 1C. In a still further embodiment the protective material (e.g.alumina) used for the coating layer 104 and the hydrophobic material(e.g. polymeric silicones or fluoropolymers) are combined into a singlelayer 108 as shown specifically in FIG. 1D.

[0064] In a further alternative embodiment individual particles of theactive composition are encapsulated by the protective material as shownin FIGS. 1E and 1F typically by spray drying the particles with theprotective material. Such spray drying techniques are well known in theart. In particular as shown specifically in FIG. 1E the substrate 100has thereon one or more layers 120 comprised of encapsulated particles122 which, as shown in FIG. 1F are comprised of the active composition102 with at least one protective layer 104 thereover optionally with atleast one layer 106 of a hydrophobic substance.

[0065] The application of the active composition and protectivematerials is described with reference to FIGS. 2 and 3. A radiatorassembly of a motor vehicle is shown in FIG. 2 including a housing 10, agrille 12, an air conditioner condenser 14, a radiator 16 and a radiatorfan 18. It will be understood that other vehicle components aretypically found in a motor vehicle.

[0066] Referring to FIG. 2, the preferred atmosphere contacting surfacesinclude the air side tube 13 and fin 15 surfaces of the air conditioningcondenser 14, as well as the air side tube 17 and fin 19 surfaces of theradiator 16. These surfaces are located within the housing 10 of a motorvehicle. They are typically under the hood of the motor vehicle betweenthe front of the vehicle and the engine. The air conditioner condenser14 and the radiator 16 can be directly or indirectly supported by thehousing 10 of the vehicle.

[0067] The surfaces 13, 15 and 17, 19 of the air conditioner condenser14 and the radiator 16, respectively can be treated in accordance withthe present invention to provide a catalytic or adsorptive surfacecovered with a protective material as described above in connection withFIGS. 1A-1E. The most preferred atmosphere contacting surface is theouter surface of the radiator 16. A typical radiator has front and rearsurfaces with spaced apart flat tubes having therebetween a plurality ofradiator corrugated plates. More specifically and referring to FIG. 3,there is shown a radiator 16 including spaced apart tubes 40 for theflow of a first fluid and a series of corrugated plates 42 therebetweendefining a pathway 44 for the flow of a second fluid transverse to theflow of the first fluid. The first fluid such as antifreeze is suppliedfrom a source (not shown) to the tubes 40 through an inlet 46. Theantifreeze enters the radiator 16 at a relatively high temperaturethrough the inlet 46 and eventually leaves the radiator through anoutlet 48. The second fluid such as air passes through the pathway 44and thereby comes into heat exchange relationship with the first fluidpassing through the tubes 40.

[0068] In accordance with the present invention, the surfaces of thecorrugated plates 42 of the radiator 16 can be treated to provide acatalytic or adsorptive surface which is protected from contaminantsincluding particulate matter, gases, water and the like.

[0069] As previously discussed, another embodiment of the invention isspecifically directed to the use of protective materials which may beovercoated on adsorptive systems (e.g., automobile radiators coated withadsorptive compositions) which are useful for cleaning the atmosphere byadsorbing pollutants particularly hydrocarbons contained in theatmosphere. The function of the protective materials is to preventadsorptive material degrading contaminants present in the atmosphere (inparticular solid or aerosol particulates, water, water borne salts andhigh molecular weight hydrocarbons) which would lead to masking,fouling, and/or poisoning of the adsorptive composition from interactingwith the adsorptive material. Since the purpose of an automobileradiator is to provide heat exchange and cooling for the engine, theradiator is usually located at the front of the vehicle where it hasample access to large volumes of ambient air. As a result, the radiatoroperates in a relatively dirty environment and is exposed to all typesof solid, gaseous and liquid airborne and roadway contaminants. Anadsorptive material applied to the radiator for purposes of adsorbingatmospheric pollutants such as hydrocarbons and carbon monoxide shouldpreferably be able to function over an extended period of time in aseverely dirty environment.

[0070] The practice of the methods of the present invention minimizecontact of airborne contaminants with the radiator adsorptivecomposition. This is accomplished by applying an overcoat of a porous,preferably adsorbent protective material on the surface of theadsorptive composition. The function of the porous protective materialis to trap and hold airborne particulates, aerosols, water borne saltsand high molecular weight hydrocarbons so that they do not come intocontact with the adsorptive material underneath. The porous protectivematerial is preferably dense enough to trap contaminants but also porousenough to allow free passage of the ambient air which contains thepollutant to be treated (e.g., hydrocarbons, carbon monoxide) to theadsorptive composition below. In this way, the adsorptive composition iskept substantially contaminant free and is therefore able to providehigh levels of long lasting pollutant adsorption. Useful and preferredadsorptive materials/compositions include zeolites such as acid and/orion exchanged and/or dealuminated zeolites examples of such zeolitesinclude but are not limited to zeolite-Y, ferrierite, zeolite-A,beta-zeolite, ZSM-5, other molecular sieves and mixtures thereof; carbonand Group IIA alkaline earth metal oxides such as calcium oxide. Theadsorbed pollutants may be subsequently collected, if desired, bydesorption, for example, followed by destruction by catalytic reactionor incineration.

EXAMPLE 1

[0071] A Ford Taurus radiator was coated in four separate sections(“quadrants”) with four MnO₂ based ozone destroying catalystformulations. A brief description of each formulation is given below:Section 1: same as Section 2 formulation without the alumina coating.

[0072] Section 2: 3.5 μm average particle size MnO₂ coating containing asilicone/acrylic binder blend and overcoated with an SRS-II aluminacoating.

[0073] Section 3: 3.5 μm particle size reference MnO₂ coating preparedfrom an unstable (i.e. coagulated) slurry formulation.

[0074] Section 4: 1 μm average particle size MnO₂ coating containing anacrylic binder without the alumina overcoat.

[0075] The MnO₂ binder system used in the Section 1 and 2 formulationscontained a 3:1 blend of acrylic/styrene acrylic latex binder (RhoplexP-376 from Rohm & Haas) with a reactive silicone latex binder resin(M-50E from Wacker Silicones Corp.). The MnO₂ binder system used in thenon-preferred reference Section 3 formulation contained an EVA (ethylenevinyl acetate) latex binder from National Starch (Duroset E-646). TheMnO₂ binder system used in the Section 4 formulation contained anacrylic latex binder from National Starch (Nacrylic X-4280). The SRS-IIalumina binder is system used in the overcoat formulation coated onSection 2 contained an acrylic/styrene acrylic latex binder from Rohm &Haas (Rhoplex P-376). The SRS-II alumina was purchased from Grace. TheBET surface area of this material was ca. 300 m²/g and it containedapproximately 5% silica. The mean particle size was approximately 7.5 μmas measured by a Horiba LA-500 Laser Diffraction Particle SizeDistribution Analyzer. The alumina overcoat was applied at a loading ofca. 0.22 g/in³ of radiator volume. The MnO₂ catalyst loadings wereapproximately 0.44 g/in³ of radiator volume.

[0076] The coated radiator was placed within an air duct and subjectedto long term aging in the presence of continuous ambient airflow. Theairflow entering the radiator was maintained at an approximate 9.5 mphlinear velocity (ca. 600,000/h radiator space velocity). The radiatorwas heated internally with hot recirculating coolant (50:50 mixture ofantifreeze and water), and the coolant temperature entering the radiatorwas maintained between 70 and 90° C. depending on the ambient airtemperature. Because of low ambient air temperature, a fraction of theair exiting the radiator was recirculated back to the radiator inlet inorder to maintain the radiator coolant temperature between 70 and 90° C.

[0077] Ozone conversion of the four different catalyst compositions wasmeasured periodically to assess any deactivation in performance overtime. This was accomplished by placing the radiator in a different testrig (air duct system) than was used to complete the long-term aging.Ozone conversion was measured at three different airflows correspondingto radiator space velocities of 200,000, 400,000 and 600,000/h.Additionally, ozone conversion was measured at three differenttemperature conditions (“90° C.”, “75° C.”, and 45° C.). For the 90° C.temperature condition, the radiator test rig was operated in“single-pass” airflow mode where 100% of the air entering the radiatorwas fresh ambient air. In this configuration the coolant temperature tothe radiator was maintained at 90° C. The ambient air entering theradiator was preheated to ca. 20-40° C. with an air pre-heater (in orderto achieve the 90° C. coolant temperature), and the air temperatureexiting the radiator was allowed to vary as the airflow was changedduring the ozone conversion measurements (i.e. the higher the airflowthe lower the air temperature). For the other temperature conditionsused to measure ozone destruction performance, the test rig was operatedin “full circulation” airflow mode where the air exiting the radiatorwas recirculated back to the radiator inlet. In this configuration, theair exiting the radiator was maintained at a constant 45 or 75° C. whileozone conversion measurements were taken at different airflows.

[0078] Initial conversion results for the four catalyst coatingformulations are shown in Table 1. Initial conversions for Sections 1,3, and 4 were virtually identical (e.g., 85% at 600,000/h space velocityand the 90° C. coolant condition), but the overcoated sample of Section2 was ca. 6% lower (78%, respectively). The radiator was aged for 14days at ambient temperature conditions (i.e. the coolant heaters wereturned off) and then the radiator was aged an additional 25 days atnormal operating temperature (i.e. 70-90° C.). Ozone conversion resultsat the completion of aging are shown in Table 2.

[0079] After aging, the section 3 coating containing the non-preferredreference catalyst formulation typically had the lowest conversion (e.g.37% at 600,000/h space velocity and the 90° C. coolant temperaturecondition). Section 4 containing the small particle catalyst formulationwas a little better (41%, respectively), and Section 1 containing thelarger particle catalyst formulation was better yet (46%, respectively).Section 2 with the overcoated catalyst formulation, however, wassignificantly better (65%, 10 respectively). At the 90° C. temperaturetest condition and a space velocity of 600,000/h, the Section 2 catalystformulation lost only an absolute 13% in ozone conversion activityduring the entire aging period while the other three lost at least anabsolute 40% (Table 3). Clearly the SRS-II alumina overcoat on Section 2had a dramatic effect on improving the long-term durability of the MnO₂catalyst underneath. This is particularly significant since the initialactivity of this section was less due to the presence of the overcoat.Despite a reduction in initial activity, the long-term activitymaintenance was excellent. TABLE 1 Temper- Space Ozone Conversion (%)ature (C) Velocity (/h) Section 1 Section 2 Section 3 Section 4 90600,000 85.0 78.3 84.5 85.0 400,000 91.4 86.4 90.9 90.7 200,000 95.592.9 98.9 95.3 75 600,000 92.8 85.6 92.4 88.0 400,000 94.7 91.0 94.792.1 200,000 97.2 95.2 97.6 96.7 45 600,000 82.2 73.1 81.9 80.1 400,00089.4 82.8 89.1 87.1 200,000 96.8 93.2 96.4 95.0

[0080] TABLE 2 Temper- Space Ozone Conversion (%) ature (C) Velocity(/h) Section 1 Section 2 Section 3 Section 4 90 600,000 46.1 65.0 37.041.0 400,000 53.7 73.0 45.0 50.5 200,000 74.4 87.5 65.5 74.4 75 600,00042.7 62.9 33.4 38.3 400,000 49.0 70.0 39.9 44.6 200,000 67.1 84.0 58.359.9 45 600,000 25.4 46.2 21.3 22.5 400,000 32.3 55.5 26.4 27.0 200,00049.9 75.5 42.2 39.2

[0081] TABLE 3 Ozone Conversion %^(a) Section 1 Fresh 85.0 Section 1Aged 46.1 Section 2 Fresh 78.3 Section 2 Aged 65.0 Section 3 Fresh 84.5Section 3 Aged 37.0 Section 4 Fresh 85.0 Section 4 Aged 41.0

EXAMPLE 2

[0082] Volvo S-70 and S-70T (turbo) radiators were coated in threeseparate sections (“stripes”) with three MnO₂ based ozone destroyingcatalyst formulations. A brief description of each formulation is givenbelow:

[0083] Section 1: 3.5 μm average particle size MnO₂ coating containing asilicone/acrylic binder blend and overcoated with SRS-II alumina.

[0084] Section 2: same as Section 1 formulation without the aluminaovercoat.

[0085] Section 3: 3.5 μm average particle size MnO₂ coating containingan EVA/acrylic binder blend and overcoated with SRS-II alumina.

[0086] The MnO₂ binder system used in the Section 1 and 2 formulationscontained a 3:1 blend of acrylic/styrene acrylic latex binder (RhoplexP-376 from Rohm & Haas) with a reactive silicone latex binder resin(M-50E from Wacker Silicones Corp.). The MnO₂ binder system used in theSection 3 formulation contained a 1:1 blend of acrylic/styrene acryliclatex binder (Rhoplex P-376 from Rhom & Haas) with an EVA (ethylenevinyl acetate) latex binder from National Starch (Duroset Elite 22). TheSRS-II alumina binder system used in the overcoat formulations coated inSections 1 and 3 contained only the acrylic/styrene acrylic latex binder(Rhoplex P-376) from Rohm & Haas. The SRS-II alumina was purchased fromGrace. The BET surface area of this material was ca. 300 m²/g and itcontained approximately 5% silica. The mean particle size wasapproximately 6.5 μm as measured by a Horiba LA-500 Laser DiffractionParticle Size Distribution Analyzer. The alumina overcoats were appliedat loadings of ca. 0.18 g/in³ of radiator volume. The MnO₂ catalystloadings were approximately 0.35 g/in³ of radiator volume.

[0087] The coated radiators were placed on Volvo S-70 and S-70 T (turbo)vehicles and subjected to accelerated on-road mileage accumulation (ca.1,000 miles per day). The radiators of both vehicles were removed afteraccumulating approximately 16,000 miles in the Detroit, Mich.metropolitan area during February 1999. The ozone conversion of thecoated sections on each radiator was evaluated to assess anydeactivation in performance over time. The radiators were thenre-installed on the vehicles, and an additional 16,000 miles wasaccumulated on each (32,000 total miles) in the Phoenix, Ariz.metropolitan area during March 1999. The radiators were once againremoved, and the ozone conversion of the coated sections on eachradiator was evaluated to further assess any deactivation in performanceover time. Finally, the radiators were re-installed on the vehicles, andan additional 18,000 miles was accumulated on each (50,000 total miles)in the Phoenix, Ariz. metropolitan area during April 1999. The radiatorswere removed one last time, and the ozone conversion of the coatedsections on each radiator was evaluated to further assess anydeactivation in performance over time.

[0088] Ozone conversion was measured by placing the radiators in afull-scale radiator test rig (air duct), heating the radiatorsinternally with hot recirculating coolant (50:50 mixture of antifreezeand water), and blowing ozone-containing air over the radiators. Ozoneconversion was measured at three different airflows corresponding toradiator space velocities of 200,000, 400,000, and 600,000/h.Additionally, the radiator test rig was operated to achieve threedifferent temperature conditions (90° C., 75° C., and 45° C.). For the90° C. condition, the test rig was operated in “single-pass” airflowmode where 100% of the air entering the radiator was fresh ambient air.In this configuration the coolant temperature to the radiator wasmaintained at 90° C. The ambient air entering the radiator was preheatedto ca. 20° C. to 40° C. (in order to maintain the 90° C. coolanttemperature), and the air temperature exiting the radiator was allowedto vary as the airflow was changed during the ozone conversionmeasurements (i.e. the higher the airflow the lower the airtemperature). For the other temperature conditions used to measure ozonedestruction performance, the test rig was operated in “fullrecirculation” airflow mode where the air exiting the radiator wasrecirculated back to the radiator inlet. In this configuration, the airexiting the radiator was maintained at a constant 45 or 75° C. whileozone conversion measurements were taken at different airflows.

[0089] Ozone conversion results fresh and after on-road aging for thethree formulations on the S-70 radiator are shown in Tables 4-8.Although both of the alumina-overcoated sections had initial lowerconversions, these sections showed substantially less decline inconversion with on-road aging. In fact, as illustrated in Table 8, theovercoated Section 3 catalyst formulation showed virtually nodeactivation over 51,000 miles whereas the non-overcoated Section 2catalyst lost an absolute 23% in ozone conversion. Although, ozoneconversion for the three sections was virtually identical after 32,000miles, after 51,000 miles, both of the overcoated catalyst formulationson Sections 1 and 3 had significantly better ozone conversion than thenon-overcoated catalyst formulation on Section 2. Additional on-roadaging would be expected to result in continued faster deactivation forthe non-overcoated formulation relative to the two overcoatedformulations. TABLE 4 Volvo S-70 Fresh Temperature Ozone Conversion (%)(C. °) Space Velocity (/h) Section 3 Section 2 Section 1 90 600,000 48.461.9 53.3 400,000 53.9 68.5 61.0 200,000 65.5 80.2 71.6 75 600,000 52.665.8 58.3 400,000 58.3 72.3 64.2 200,000 70.3 80.0 75.0 45 600,000 41.751.4 43.5 400,000 47.1 61.6 50.2 200,000 63.4 74.5 67.5

[0090] TABLE 5 Volvo S-70 aged 16,140 miles Temperature Ozone Conversion(%) (C. °) Space Velocity (/h) Section 3 Section 2 Section 1 90 600,00049.7 51.9 51.7 400,000 55.0 61.5 60.0 200,000 67.7 74.3 71.4 75 600,00050.8 50.8 50.6 400,000 55.8 59.7 58.3 200,000 72 4 76.3 73.7 45 600,00045.6 49.6 45.3 400,000 50.8 52.0 50.1 200,000 63.2 68.1 65.8

[0091] TABLE 6 Volvo S-70 aged 32,087 miles Temperature Ozone Conversion(%) (C. °) Space Velocity (/h) Section 3 Section 2 Section 1 90 600,00047.6 45.7 46.7 400,000 53.1 51.6 53.4 200,000 65.9 65.6 65.6 75 600,00048.3 44.1 47.3 400,000 57.0 54.9 56.9 200,000 71.4 67.9 69.5 45 600,00044.7 36.9 38.3 400,000 48.8 43.9 46.1 200,000 64.7 57.4 60.0

[0092] TABLE 7 Volvo S-70 aged 50,863 miles Temperature Ozone Conversion(%) (C. °) Space Velocity (/h) Section 3 Section 2 Section 1 90 600,00047.5 39.0 43.9 400,000 54.2 49.6 53.0 200,000 67.8 63.0 67.2 75 600,00049.9 39.5 47.0 400,000 60.3 49.9 54.7 200,000 71.3 62.0 70.5 45 600,00041.2 26.2 29.9 400,000 47.3 33.3 40.0 200,000 60.8 46.9 55.5

[0093] TABLE 8 Ozone Conversion %^(b) Section 1 Fresh 53.3 Section 1Aged 16,140 miles 51.7 Section 1 Aged 32,087 miles 46.7 Section 1 Aged50,863 miles 43.9 Section 2 Fresh 61.9 Section 2 Aged 16,140 miles 51.9Section 2 Aged 32,087 miles 45.7 Section 2 Aged 50,863 miles 39.0Section 3 Fresh 48.4 Section 3 Aged 16,140 miles 49.7 Section 3 Aged32,087 miles 47.6 Section 3 Aged 50,863 miles 47.5

[0094] Similar fresh and aged ozone conversion results for the samethree formulations coated on the S-70 T radiator are shown in Tables9-13. Although all sections showed some decline in activity with on-roadaging, the overcoated sections declined at a significantly slower rate.In fact, as illustrated in Table 13, the overcoated Section 1 and 3catalyst formulations showed an absolute loss in ozone conversion ofapproximately 13% after 50,000 miles whereas the non-overcoated Section2 catalyst lost an absolute 22% in ozone conversion. In addition, after50,000 miles, both of the alumina overcoated catalyst formulations(particularly the Section 3 catalyst) had higher ozone conversion thanthe non-overcoated catalyst formulation. Additional on-road aging wouldbe expected to result in continued faster deactivation for thenon-overcoated formulation relative to the two overcoated formulations.TABLE 9 Volvo S-70T Fresh Temperature Ozone Conversion (%) (C. °) SpaceVelocity (/h) Section 3 Section 2 Section 1 90 600,000 67.2 67.0 60.5400,000 75.8 73.7 68.2 200,000 85.1 85.4 82.0 75 600,000 62.4 60.7 53.2400,000 68.3 67.3 62.7 200,000 83.1 82.9 80.2 45 600,000 53.0 50.7 43.6400,000 62.3 61.2 55.4 200,000 77.4 76.2 72.2

[0095] TABLE 10 Volvo S-70T aged 16,233 miles Temperature OzoneConversion (%) (C. °) Space Velocity (/h) Section 3 Section 2 Section 190 600,000 56.8 50.5 51.1 400,000 63.7 60.1 59.5 200,000 81.8 78.6 77.475 600,000 57.4 54.2 52.2 400,000 65.0 61.8 60.8 200,000 80.4 77.7 77.045 600,000 47.6 42.5 40.2 400,000 56.5 50.7 50.3 200,000 74.7 69.5 69.8

[0096] TABLE 11 Volvo S-70T aged 32,277 miles Temperature OzoneConversion (%) (C. °) Space Velocity (/h) Section 3 Section 2 Section 190 600,000 57.7 48.1 48.7 400,000 63.6 57.4 58.3 200,000 76.9 71.5 72.475 600,000 56.9 50.4 50.3 400,000 67.2 59.2 60.5 200,000 79.8 71.7 73.945 600,000 48.4 37.8 38.0 400,000 50.9 46.0 44.6 200,000 66.8 59.3 58.7

[0097] TABLE 12 Volvo S-70T aged 50,173 miles Temperature OzoneConversion (%) (C. °) Space Velocity (/h) Section 3 Section 2 Section 190 600,000 54 4 45.0 46.9 400,000 61.7 52.0 53.4 200,000 78.0 69.9 72.075 600,000 55.9 43.1 46.6 400,000 64.1 51.5 55.8 200,000 80.0 69.4 74.445 600,000 42.0 29.9 32.3 400,000 49.4 37.3 42.5 200,000 67.1 53.8 59.8

[0098] TABLE 13 Ozone Conversion %^(c) Section 1 Fresh 60.5 Section 1Aged 16,233 miles 51.1 Section 1 Aged 32,277 miles 48.7 Section 1 Aged50,173 miles 46.9 Section 2 Fresh 67.0 Section 2 Aged 16,233 miles 50.5Section 2 Aged 32,277 miles 48.1 Section 2 Aged 50,173 miles 45.0Section 3 Fresh 67.2 Section 3 Aged 16,233 miles 56.8 Section 3 Aged32,277 miles 57.7 Section 3 Aged 50,173 miles 54.4

EXAMPLE 3

[0099] A Ford Taurus radiator was coated in three separate sections(“stripes”) with three MnO₂ based ozone destroying catalystformulations. A brief description of each formulation is given below:

[0100] Section 1: 3.5 μm average particle size MnO₂ coating containingan EVA/acrylic binder blend and overcoated with SRS-II alumina.

[0101] Section 2: same as Section 1 formulation without the aluminaovercoat.

[0102] Section 3: 3.5 μm average particle size MnO₂ coating containingan EVA/acrylic binder blend and overcoated with SRS-II alumina andfurther overcoated with FC-824 water repellent.

[0103] The MnO₂ binder system used in all sections contained a 1:1 blendof acrylic/styrene acrylic latex binder (Rhoplex P-376 from Rhom & Haas)with an EVA (ethylene vinyl acetate) latex binder from National Starch(Duroset Elite 22). The SRS-II alumina binder system used in theovercoat formulations coated in Sections 1 and 3 contained only theacrylic/styrene acrylic latex binder (Rhoplex P-376) from Rohm & Haas.The SRS-II alumina was purchased from Grace. The BET surface area ofthis material was ca. 300 m²/g and it contained approximately 5% silica.The mean particle size was approximately 6.5 μm as measured by a HoribaLA-500 Laser Diffraction Particle Size Distribution Analyzer. Thealumina overcoats were applied at loadings of ca. 0.22 g/in³. The MnO₂catalyst loadings were approximately 0.38 g/in³ of radiator volume.

[0104] The FC-824 water repellent was purchased from 3M Corporation, andit comprised a proprietary fluoropolymer latex emulsion in water. Thisemulsion was diluted to 2.5% solids in water and was subsequentlysprayed onto the Section 3 catalyst formulation such that the catalystcoating was thoroughly wetted. Excess solution was then removed with anairknife, and the entire radiator was then dried at 90° C. forapproximately 1 hour.

[0105] The coated radiator was placed on a Ford Taurus vehicle andsubjected to accelerated on-road mileage accumulation (ca. 1,000 milesper day). The radiator was removed after accumulating 18,000 miles inthe Phoenix, Ariz. metropolitan area during April 1999. The ozoneconversion of the coated sections on the radiator was evaluated toassess any deactivation in performance over time. The radiator was thenre-installed on the vehicle, and an additional 18,000 miles wasaccumulated (36,000 total miles) in the Phoenix, Ariz. metropolitan areaduring May 1999. The radiator was once again removed, and the ozoneconversion of the coated sections on the radiator was evaluated tofurther assess any deactivation in performance over time. Finally, theradiator was re-installed on the vehicle, and an additional 14,000 mileswas accumulated (50,000 total miles) in the Detroit, Mich. metropolitanarea during June 1999. The radiator was removed one last time, and theozone conversion of the coated sections on the radiator was evaluated tofurther assess any deactivation in performance over time.

[0106] Ozone conversion was measured by the same procedure described inExamples 1 and 2.

[0107] Ozone conversion results fresh and after on-road aging for thethree formulations on the Ford Taurus radiator are summarized in Table14. Although all sections showed some decline in activity with on-roadaging, the two overcoated sections declined at a slower rate. Asillustrated in Table 14, the overcoated Section 1 and 3 catalystformulations showed an absolute loss in ozone conversion of 15 and 8%,respectively, after 50,000 miles whereas the non-overcoated Section 2catalyst lost an absolute 19% in ozone conversion. Clearly, theovercoated catalyst formulations, particularly the Section 3 catalystformulation with the combination of alumina and water repellent,deactivated the least after 50,000 miles of on-road aging. In addition,both of the overcoated catalyst formulations had higher ozone conversionafter 50,000 miles aging than the non-overcoated catalyst formulation.Additional on-road aging would be expected to result in continued fasterdeactivation for the non-overcoated formulation relative to the twoovercoated formulations. TABLE 14 Ozone Conversion %^(d) Section 1 Fresh84.4 Section 1 Aged 18,506 miles 77.0 Section 1 Aged 36,168 miles 74.7Section 1 Aged 50,335 miles 69.0 Section 2 Fresh 84.7 Section 2 Aged18,506 miles 81.1 Section 2 Aged 36,168 miles 77.0 Section 2 Aged 50,335miles 65.7 Section 3 Fresh 76.5 Section 3 Aged 18,506 miles 70.8 Section3 Aged 36,168 miles 73.0 Section 3 Aged 50,335 miles 68.4

What is claimed:
 1. A method of cleaning the atmosphere either bycatalytically treating the atmosphere to convert atmospheric pollutantsto less harmful materials or by adsorbing pollutants contained in theatmosphere comprising contacting the pollutant containing atmospherewith an outer surface of a substrate which has been coated with either acatalyst composition to render said surface capable of catalyticallyconverting said atmospheric pollutants into less harmful materials or anadsorptive composition in order to render said surface capable ofadsorbing said atmosphere components and protecting the catalyst and/oradsorbent coated surface with an overcoat of at least one porousprotective material which is sufficiently porous to enable saidatmospheric containing said pollutants to pass therethrough intooperative contact with the catalyst and/or adsorbent composition andwhich is sufficiently protective to prevent harmful contaminants fromcontacting the catalyst and/or adsorbent composition.
 2. A method ofcleaning the atmosphere by catalytically treating the atmosphere toconvert atmospheric pollutants to less harmful materials comprisingcontacting the pollutant containing atmosphere with an outer surface ofa substrate which has been coated with a catalyst composition to rendersaid surface capable of catalytically converting said atmosphericpollutants into less harmful materials and protecting the catalystcoated surface with an overcoat of at least one porous protectivematerial which is sufficiently porous to enable said atmosphericcontaining said pollutants to pass therethrough into operative contactwith the catalyst composition and sufficiently protective to preventharmful contaminants from contacting the catalyst composition.
 3. Themethod of claim 2 further comprising coating the porous protectivematerial overcoated catalytic surface with at least one hydrophobicprotective substance which is capable of substantially preventing liquidwater and/or water vapor from reaching the catalyst composition.
 4. Themethod of claim 2 comprising catalytically treating the atmosphere attemperatures of from about 0°-to about 150° C.
 5. The method of claim 2wherein the catalyst composition comprises base metals, precious metalsas well as salts and oxides thereof and combinations thereof.
 6. Themethod of claim 2 wherein the catalyst composition comprises manganesedioxide.
 7. The method of claim 2 wherein the porous protective materialis selected from the group consisting of zeolites, clays, alumina,silica, alkaline earth oxides, rare earth oxides, carbon and inert metaloxides and mixtures thereof.
 8. The method of claim 7 wherein the porousprotective material is silica containing high surface area alumina. 9.The method of claim 3 wherein the hydrophobic substance is selected fromthe group comprising fluoropolymers and silicone polymers.
 10. A devicefor cleaning the atmosphere by catalytically treating the atmosphere toconvert atmospheric pollutants to harmless byproducts comprising: a) asubstrate having a surface; b) a catalyst composition coated on saidsurface; and c) at least one porous protective material coated over thecatalyst composition, said porous protective material being sufficientlyporous to enable said atmosphere containing pollutants to passtherethrough into operative contact with the catalyst composition andsufficiently adsorbent to prevent harmful contaminants from contactingthe catalyst composition.
 11. The device of claim 10 further comprisingat least one hydrophobic protective material overcoating the porousprotective material which is capable of substantially preventing liquidwater and/or water vapor from reaching the catalyst composition.
 12. Thedevice of claim 10 comprising at least one layer of a protectivematerial over the catalyst composition.
 13. The device of claim 11comprising at least one layer of the porous protective material and atleast one layer of the hydrophobic protective material coated over thecatalyst composition.
 14. The device of claim 13 wherein at least onelayer containing the hydrophobic protective material is between thelayer of porous protective material and the catalyst composition. 15.The device of claim 10 wherein the catalyst composition comprises basemetals, precious metals as well as salts and oxides thereof andcombinations thereof.
 16. The device of claim 10 wherein the catalystcomposition comprises manganese dioxide.
 17. The device of claim 10wherein the porous protective material and the hydrophobic protectivematerial are contained within at least one single layer.
 18. The deviceof claim 10 wherein the porous protective material is selected from thegroup consisting of zeolites, clays, alumina, silica, alkaline earthoxides, rare earth oxides, carbon and inert metal oxides.
 19. The deviceof claim 10 wherein the porous protective material is chosen fromalumina or a silica containing high surface area alumina.
 20. The deviceof claim 10 wherein the porous protective material is alumina and thecatalyst composition comprises manganese dioxide.
 21. The device ofclaim 10 wherein the pollutants to be treated are selected from thegroup comprising ozone, hydrocarbons, carbon monoxide and mixturesthereof.
 22. The device of claim 11 wherein the hydrophobic protectivematerial is selected from the group consisting of fluoropolymers andsilicone.
 23. A method of cleaning the atmosphere by adsorbingpollutants contained in the atmosphere comprising contacting thepollutant containing atmosphere with an outer surface of a substratewhich has been coated with an adsorptive material to render said surfacecapable of adsorbing said atmospheric pollutants and protecting theadsorptive material coated surface with an overcoat of at least oneporous protective material which is sufficiently porous to enable saidatmosphere containing said pollutants to pass therethrough intooperative contact with the adsorptive material and sufficientlyprotective to prevent harmful contaminants from contacting theadsorptive material.
 24. The method of claim 23 further comprisingcoating the porous protective material overcoated surface with at leastone hydrophobic protective substance which is capable of substantiallypreventing liquid water and/or water vapor from reaching the adsorptivematerial.
 25. The method of claim 23 wherein the adsorptive material ischosen from among zeolites, molecular sieves, carbon and Group IIA metaloxides.
 26. The method of claim 23 wherein the adsorptive material is azeolite.
 27. The method of claim 26 wherein the zeolite is beta-zeolite.28. The method of claim 23 wherein the porous protective material isselected from the group consisting of zeolites, clays, alumina, highsurface area alumina silica, alkaline earth oxides, rare earth oxides,carbon and inert metal oxides and mixtures thereof.
 29. The method ofclaim 24 wherein the hydrophobic substance is selected from the groupcomprising fluoropolymers and silicone polymers.
 30. A device forcleaning the atmosphere comprising: a) a substrate having a surface; b)an adsorptive material coated on said surface; and c) at least oneporous protective material coated over the adsorptive material, saidporous protective material being sufficiently porous to enable saidatmosphere-containing pollutants to pass therethrough into operativecontact with the adsorptive material and sufficiently protective toprevent harmful contaminants from contacting the adsorptive material.31. The device of claim 30 further comprising at least one hydrophobicprotective material overcoating the porous protective material which iscapable of substantially preventing liquid water and/or water vapor fromreaching the adsorptive material.
 32. The device of claim 31 comprisingat least one layer of the porous protective material and at least onelayer of the hydrophobic protective material coated over the adsorptivematerial.
 33. The device of claim 30 wherein the adsorptive material isselected from zeolites, molecular sieves, carbon and Group IIA metaloxides and combinations thereof.
 34. The device of claim 30 wherein theadsorptive material is a zeolite.
 35. The device of claim 30 wherein theporous protective material is selected from the group consisting ofzeolites, clays, alumina, silica, alkaline earth oxides, rare earthoxides, carbon and inert metal oxides.
 36. The device of claim 30wherein the porous protective material is high surface area alumina.